This invention relates to an apparatus for measuring the sliver thickness in a drawing frame, particularly in a regulated drawing frame. The apparatus includes a sliver guiding device for guiding a plurality of simultaneously inputted fiber slivers at the inlet of the drawing frame. At least parts of the inner wall faces of the guiding device converge such that the side-by-side running slivers are brought together to form a sliver assembly in which the slivers assume a side-by-side contacting relationship in a single plane. Downstream of the guiding device, as viewed in the direction of sliver run, a roller pair is arranged which defines a nip through which the sliver assembly passes. By virtue of the frictional engagement in the nip, the roller pair pulls the sliver assembly through the sliver guiding device. Downstream of the roller pair the slivers diverge from one another. The sliver guiding device is associated with a biased, movable sensor element which, together with an operationally stationary counterelement (wall element), constitutes a constriction for the throughgoing sliver assembly. The sensor element executes excursions as the thickness of the sliver assembly changes. The displacements of the sensor element are applied to a transducer which, in response, generates control pulses. The counterelement situated opposite the sensor element may be adjusted and immobilized in its adjusted position.
In a known arrangement of the above-outlined type the counterelement is shiftable towards or away from the sensor element and may be immobilized in its adjusted position by a setscrew. The purpose of such an adjustment is to adapt the sliver guiding device to different fiber batches, particularly when the type of fiber is changed or the number of the parallel running slivers is altered.